Add support for Error.prototype.cause

[shortercode]

Relates to #294

Modifies the isDeep call to match Error objects, so that causes are correctly serialised.
Adds the cause field to serialised Error format and the deserialiser.

[Skn0tt]

Thanks for the PR! Looks good generally, but please add some tests to convince me this works as intended.

[shortercode]

Thanks for the PR! Looks good generally, but please add some tests to convince me this works as intended.

Apologies @Skn0tt been rather side tracked on other work. Is the test I've added sufficient or would you like a more comprehensive set?

For context we use electron-trpc and frequently pass Result style objects back to our renderer thread. This change will allow us to preserve our error causes which hold a lot more useful information than the stack.

[matthew-magical]

@shortercode Thanks for making this PR as I'm encountering the same limitation.
@Skn0tt not sure if you saw the question above?

[Skn0tt]

Looks good, thanks!